Field of the Invention
Embodiments of the present invention relate generally to electricity grid architecture, and, more specifically, to determining electric grid topology via a zero crossing technique.
Description of the Related Art
FIG. 1 illustrates a conventional three-phase power distribution network 100, according to the prior art. As shown, power distribution network 100 typically includes a power generator 110 coupled via power lines 120 to a three-phase power consumer 130.
Power generator 110 is usually some sort of power plant, such as a hydroelectric dam or a nuclear power station. Power generator 110 includes different coils 112, 114, and 116 that are configured to generate power having specific voltages, currents, and phases. Coil 112 generates power having a voltage V1 and a current I1, where that current alternates with phase A. Similarly, coil 114 generates power having a voltage V2 and a current I2, where that current alternates with phase B, and coil 116 generates power having a voltage V3 and a current I3, where that current alternates with phase C. Coils 112, 114, and 116 transmit power across power lines 120-1, 120-2, and 120-3, respectively, to three-phase power consumer 130.
Three-phase power consumer 130 may be an industrial facility that operates heavy machinery, such as large three-phase motors, heating elements, pumps, and so forth, or a commercial enterprise that requires three-phase power, such as a shopping mall or supermarket. Three-phase power consumer 130 includes loads 132, 134, and 136 that receive power across power lines 120-1, 120-2, and 120-3. Load 132 receives power from power lines 120-1 and 120-2 and is subject to current I12. Similarly, load 134 receives power from power lines 120-2 and 120-3 and is subject to current I23, and load 136 receives power from power lines 120-3 and 120-1 and is subject to current I31.
Various single-phase power consumers are also coupled to power lines 120 and configured to draw power therefrom. As shown, single-phase power consumer 140 is coupled to power line 120-1 and configured to draw power therefrom, single-phase power consumers 142 and 144 are coupled to power line 120-2 and configured to draw power therefrom, and single-phase power consumers 146, 148, and 150 are coupled to power line 120-3 and configured to draw power therefrom. A single-phase power consumer may be a house, a housing subdivision, an apartment complex, and so forth. The particular power line 120 to which each power consumer is coupled is referred to herein as the “grid topology.”
During operation, maintaining relatively consistent loading across power lines 120 is desirable for several reasons. First, balancing the loads across power lines 120 minimizes resistive losses within three-phase power consumer 130, thereby improving operating efficiency. Second, balanced loading may prevent a situation where one power line 120 is underloaded and another power line 120 is overloaded and therefore subject to failure. In view of these reasons, among others, the utility provider responsible for managing distribution network 100 may adjust the grid topology in order to equalize the loading across power lines 120. In doing so, the utility provider may migrate single-phase power consumers from one power line 120 to another power line, thereby altering the loading of those power lines.
In order to accurately adjust the grid topology, the utility provider must first positively identify which single-phase loads are coupled to which power lines 120. Typically, the utility provider dispatches servicemen to “walk the lines” and visually inspect the coupling between single-phase power consumers and power lines 120. Based on this visual inspection, the utility provider records the grid topology. Then, the utility provider migrates single-phase power consumers between power lines in an effort to equalize loading across those power lines.
The approach outlined above is problematic because visually inspecting power lines to determine grid topology is very time-consuming and costly. Moreover, the grid topology determined via this type of approach is oftentimes incorrect/inaccurate due to human error. Consequently, among other things, utility providers typically cannot effectively balance loads across the different power lines within the power distribution network 100, with a reasonable degree of accuracy, which limits the efficiency of three-phase power consumer 130 and increases the susceptibility of power lines 120 to failure.
As the foregoing illustrates, what is needed in the art is a more effective approach for determining the topologies of power distribution networks.